#include <stdio.h>
#include <string.h>
#define MAXN 1000000
int lamps[MAXN];
int all[100];

int main()
{
    int n;
	int count;
	int cc = 0;
    while(scanf("%d", &n) != EOF)
    {
		count = 0;
        int i, j;
		
        for(i = 1; i <= n; ++i)
		{
			lamps[i] = 1;
			count++;
		}
            
        for(i = 2; i <= n; ++i)
            for(j = 1; j * i <= n; ++j)
			{
				lamps[i*j] ^= 1;
				if(lamps[i*j]) count++;
				else count--;
			}

		all[cc] = count;
		cc++;
    }
	for (int i = 0; i < cc; i++)
		printf("%d\n", all[i]);
    return 0;
}
